Spring ring



Aug. 28, 1962 TAKASHI MINEGISHI SPRING RING Filed Dec. 16, 1959 4 Sheets-Sheet 1 FIG. ID

Aug. 28, 1962 TAKASHI MINEGISHI 3,051,499

SPRING RING Filed Dec. 16, 1959 4 Sheets-Sheet 2 Aug. 28, 1962 TAKASHI MINEGISHI SPRING RING 4 Sheets-Sheet 5 Filed Dec. 16, 1959 28, 1962. TAKASHI MINEGISHI 3,051,499

SPRING RING 4 Sheets-Sheet 4 Filed Dec. 16, 1959 m m6 M? 5 m G. W & W, 4 4 7 1\ w 1 .f v 3 /I5 MT m United States 3,051,499 SPRING RING Takashi Minegishi, Kawagoe City, Japan, assignor to Nippon Piston Ring Kabushiki Kaisha, Tokyo, Japan Filed Dec. 16, 1959, Ser. No. 859,948 Claims priority, application Japan Jan. 14, 1959 4 Claims. (Cl. 277140) The present invention relates to a spring piston ring comprising an open ring made from a band steel or the like steel strip, having suitable dimensions, bent in a channel form, and having a gap between the opposite ends thereof, said ring being provided with a number of slits arranged at equal intervals which extend from the outer rim of the upper flange and the lower flange, alternately, to the inner web between said two flanges, the latter being provided with vertical small projections which project outwardly at equal intervals along the inner edgeline of said flanges (i.e. the edge-lines of said inner web) so as to be in contact with the inner peripheral surface of side rails overlapping the upper and lower flanges respectively.

With recent developments in internal combustion engines, the running speeds have been greatly increased. Thereby, material used for piston rings must have a higher tensile strength, and it is diflicult to satisfy the tensile strength requirement by conventional cast iron rings, particularly with respect to the strength and high efliciency. Because, the conventional ring is made from cast-iron in spite of requiring high stress thereon, there is a certain limit of tensile stress of the material itself. Therefore, in the case of recent high speed engines, the piston rings cannot stand the high compression to which they are subjected and they do not maintain true contact with a cylinder wall. When the tensile strength of the ring, particularly in the case of the oil ring, is insufficient to scrape the oil, it is the cause of troubles of the internal combustion engine and the oil comes up into the combustion chamber and burns therein. Therefore, in order to avoid the aforesaid fault a cast-iron oil ring assembly having combined plate-spring type expanders or a spacer joining together with a side rail made from steel plate and with a plate-spring type expander therein is usually used, so as to promote the tensile strength of the oil ring. However, these expanders are normally made from steel plate in the shape of hexagon or octagon, so that the ring is strengthened by the expander in such a way that each of the outside vertexes of the expander presses only the part of the vertexes which are in contact with the inside ring or the side rail, and each of the middle portion of the two adjoining vertexes is in partial contact with the bottom surface of the piston slot. In other words, only the several parts of the expander are in partial contact with the bottom surface of the piston slot and the inside of the ring respectively, so that the pressure which is subjected to the expander is not uniform but partial all over its periphery. Therefore in consequence, elasticity of the ring varies from a portion to portion, while it is urgently required that the oil ring is forced to be in contact with the inside wall of the cylinder with uniform pressure. Viewed from the aforesaid important point, the conventional method of combining an expander with a piston ring has the essential defect which can not be free from the constitution of the expander itself. And, furthermore it is allowable that the diameter of the ring slot and of the side rail is approximately 0.2. mm. respectively, so that the difference of the tensile stress in the ring tends to be more increased when the errors depending on these allowances are combined. The present invention is directed to a novel piston ring which will be clear of the disadvantages stated above.

Explaining the outline of this invention, the present invention relates to a spring ring characterized by that it comprises an open ring made from a band steel or the like steel strip, having a suitable thickness, bent in a channel form, and having a gap between the opposite ends thereof, said ring being provided with a number of alternately arranged slits which extend inwardly from upper and lower flanges to an inner web of said channel ring and which latter is provided with a number of vertical small projections which project outwardly from the surfaces of said flanges along an edge of an inner periphery thereof to engage inner peripheral surfaces of side rails assembled thereon. The object of the present invention is to provide a cheap and mass produced spring ring which has high tensile stress in the spring body itself, said tensile stress being uniform all over the circumference thereof, and moreover, an outer periphery of said spring ring being in uniformly forced contact with an inside wall of a cylinder.

In the drawings:

FIGS. 1A through ID are plan views of four embodiments of the invention, illustrated before bending of a metal strip into the shape of a channel piston ring;

FIGS. 2A through 2D are enlarged partial views of piston rings formed from the strips shown in FIGS. 1A through 1D, respectively;

FIGS. 3A through 3D are partial views of piston rings formed from strips shown in FIGS. 1A through 1D, respectively;

FIG. 4 is a plan view, partly broken away, of an as sembly including the spring ring of the invention and associated parts; and

FIG. 5 is an enlarged radial sectional view of a piston ring assembly embodying the invention.

Now referring to the accompanying drawings, there are many embodiments according to the present invention and more ring manufacturing methods. However, in the accompanying drawings, four kinds of embodiments A, B, C and D are exemplified. Now, the spring rings A, B, C and D shown in FIGS. 1A through ID are made from the corresponding prefabricated steel plates or strips A, B, C and D illustrated in FIGS. 2A through 2D respectively, wherein said prefabricated plates are deformed to the form of the corresponding steel channels A, B, C and D having arranged slits which are seen in FIGS. 3A through 3D respectively, said steel channels being bent in the form of the open ring having a gap between the opposite ends thereof. Utilizing the spring ring A as representative of all of the springs, in order to make the channel ring from the material by means of the fabrica tion in accordance with the object of the invention, the band steel in which has a suitable thickness, depending on the kind and size of the desirable piston ring or steel strip m, is precut to a suitable dimension, and used as the material for the rings. The steel plate In is provided with a number of equally spaced equally dimensioned slits 2 formed by means of punching or the like. The slits 2 extending inwardly from opposite edge-lines 1 to the inside of said steel plate In as shown in A of FIG. 2. A number of small projections 4 are formed at the inner end of and parallel to the slits 2 by punching along the dotted bending lines 3 of the plate m. The projections 4 project outwardly in vertical direction when the steel plate m is bent in the form of the channel as indicated in FIG. 3A. According to the above described process, the prefabricated steel plate shown in FIG. 2A is manufactured. The size and the relative position of the slits 2 and the small projections 4 may be chosen freely, wherein, in the case of the spring ring A, each slit 2 extends inwardly from one side edge to the inside across the opposite side bending line 3, and each projection 4 is positioned in each slit. A series of upper and the lower flanges 5 and 6 of the channel are made by bending both sides of the' prefabricated plate at approximately right angles in the same direction along the bending lines 3. Then, on the upper and the lower flanges 5 and 6 of the channel, a number of the slits 2, which are all of equal form are arranged alternately and symmetrically at equal distance from each other, and extend to the opposite boundary of the web 7 of the channel, wherein the part of the slits which extend to the web, forms oil holes 2 (FIG. 3A) arranged at equal distances from each other, each of which has the same size. On the other hand the said channel steel is also provided with a number of small projections arranged on the surface thereof along the bending lines 3 from each other.

The channel steel indicated in FIG. 3A, i fabricated by bending the said small projections of the said prefabricated channel at approximately right angles outwardly. By cutting this fabricated channel steel in a desirable length, and by bending it in the form of an open ring with a gap, thus the spring ring shown in FIG. 1A, according to the present invention is manufactured. After these processes of manufacturing, the above-stated ring is suitably heat-treated and adjusted properly as well as known conventional practices, the spring ring of the present invention being obtained. The usage of the spring ring is following: the spring ring is set into the piston slot G as shown in enlarged view of FIG. 5, the spring ring being inserted between two sheets of side rails S, inner periphery surfaces of which are in contact with the outer surfaces of the small projections arranged in circle along the edge-line of said spring ring to arrest the said side rails as shown in FIG. 4.

The channel steel shown in FIG. 3B is fabricated by bending the prefabricated plate B according to the object of the invention, as well as in the case of manufacturing spring ring A. In the above case said prefabricated plate B is provided with a number of slits 2 and small projections 4 arranged in such a way that their position and size are shown in FIG. 2B, wherein projections 4 are positioned connecting to side of the deepest end of slits 2. Thus the present spring ring B indicated in FIG. 1C can be obtained by bending said channel steel in the form of an open ring with a gap.

If the prefabricated plate is provided with the small projections 4 arranged in the slits 2 and positioned near the mouth of said slits as shown in C of FIG. 2C, the present spring ring C seen in FIG. 1C can be manufactured by bending the channel steel in the form of an open ring with a gap according to the gist of the present invention, said channel steel shown in C of FIG. 3C being fabricated by means of deforming the said prefabricated plate C.

In the case that the prefabricated plate is provided with the projections 4, being arranged at the middle portion between the adjoining slits 2 as represented in FIG. 2D,

the present spring ring D shown in FIG. 1D is made from said prefabricated plates by means of deforming in the shape of an open ring with a gap, after bending to make the channel steel having arranged slits shown in FIG. 3D.

Of each ring above mentioned, the outside diameter of the small projections 4 arranged in circle is slightly larger than the inside diameter of the side rail S, so as to press the small projections on the spring ring to the side rail S and to force the spring ring to exhibit the elasticity, the side rail S being made a little thicker than that of the projections 4. The said spring ring and side rails are combined so as not to be overlapped on the gap of each part.

As explained in the foregoing description, the embodiment according to this invention, i.e. the spring ring, is characterized in that not only it possesses high elasticity and best expansive efficiency but also it is subjected to the uniform elasticity all over the periphery of the ring, became a number of identical slits are symmetrically arranged on the channel ring at the same distance from each other. The compressing force, by which the side rails are pressed to the inner surface of the cylinder, being transmitted from the inner surfaces of the projections to the side rails, is higher and more uniform than compression subjected thereto by means of the conventional manner. Hence, the present spring ring provides not only an excellent piston ring having an important and essential condition thereof, but also an effective oil ring by which the oil does not come up to the combustion chamber, even if used in the modern high speed internal combustion engine, while in the case of the conventional cast-iron oil ring the oil often comes up. Also the present spring ring has a great effect of being in uniform contact. In contrast with the conventional plate-spring type expander it is unnecessary for the present spring ring that the spring body is in contact with the bottom surface of the piston slot, so that the surface of the cylinder and the piston are not so much abraded by the remaining gap between the slot bottom and the ring to allow the ring to move even if the extraordinary pressure is subjected to the side rail on account of the vibration of the piston during operation. According to the above good point, the finishing accuracy of the piston slot may be chosen somewhat lower than standard. The spring ring according to the present invention is manufactured from the steel strip by punching off the slits and bending it in the desirable shape of the channel, as the result the bottom parts of said slit become naturally the oil hole thereof, so that manufacturing thereof is very simple, quick and mass-productive. Therefore, the present invention provides a wonderful economical effect of supplying the excellent oil ring cheaply and mass-productively.

I claim:

1. A piston ring assembly comprising in combination upper and lower rails spaced apart at an interval in an axial direction, and a spacer expander keeping said rails at said interval, said spacer expander being of channel shape and comprising circumferentially spaced upper and lower flanges for receiving each rail and straight webs connected between said flanges defined by slits cut therein throughout their length from each edge of said flanges alternately and symmetrically, with a small axial projection defined at the end of each of said slits on the inner periphery of said flanges, said projections extending outwardly adjacent said rails, each of said rails being pressed by said projections outwardly in a radial direction, respective projections bearing against the rail nearest the end of the slit which defines said projections.

2. A piston ring assembly comprising in combination upper and lower rail spaced apart at an interval in an axial direction, and a spacer expander keeping said rails at said interval, said spacer expander being of channel shape and comprising upper and lower flanges for receiving each rail and straight webs connected between said flanges defined by slits cut therein throughout their length from each edge of said flanges alternately and symmetrically, said slits being made of equal width by narrowing each of said slits towards the edge of cut from the web, a small axial projection at the end of each of said slits on an inner periphery of said flanges, said projection extending axially outwardly adjacent said rails, and each of said rails on said flanges being pressed by a row of said projections outwardly in radial direction, respective projections bearing against the rail nearest the end of the slit which defines said projections.

3. A piston ring comprising a continuous strip including upper and lower flange portions in axially spaced relation, webs joining the ends of each of said upper flange portions with the next adjacent ends of said lower flange portions, projections formed as extensions of said upper and lower flange portions at locations intermediate the length thereof and extending axially outwardly in directions away from said connecting webs, said flange portions having side edges diverging outwardly from said connecting webs, circumferentially adjacent flange portions and webs being separated by radial slots extending alternately in opposite radial directions of said ring and each having a closed end in a flange portion, the projections of each flange portion being adjacent the respective closed end of a slot.

4. A piston ring assembly comprising in combination upper and lower rails spaced apart at an interval in an axial direction, and a spacer expander keeping said rails at said interval, said spacer expander being of channel shape and comprising circumferentially spaced upper and lower flanges for receiving each rail and straight webs connected between said flanges defined by slits out therein throughout their length from each edge of said flanges alternately and symmetrically, each slit having a closed end in a respective flange, with a small axial projection defined at the closed end of each of said slits on the 6 inner periphery of said flanges, said projections extending axially outwardly adjacent said rails, each of said rails being pressed by said projections outwardly in a radial direction, said upper and lower flanges having side edges which diverge outwardly from said webstructure.

References Cited in the tile of this patent UNITED STATES PATENTS 2,421,175 Zahodiakin May 27, 1947 2,768,039 Cable Oct. 23, 1956 2,777,740 Pien Jan. 15, 1957 2,833,604 Hunt May 6, 1958 2,833,605 Shirk May 6, 195 2,837,385 Mayfield June 3, 1958 2,837,386 Mayfield June 3, 1953 

